Unsure about what the role of NATO has been in those 70 years? Here's our handy timeline of key events in NATO'S history.
The North Atlantic Treaty Organization is founded as a defence alliance against the Soviet Union and their plans for European expansion.
West Germany joins NATO, prompting the Soviet Union eight days later to gather eight east European nations into the Warsaw Pact coalition.
France and Great Britain use troops to intervene, against the wishes of the United States, causing a rift in NATO.
NATO and the United States demonstrate the size and efficiency of emergency forces by flying 14,500 US troops flown into West Germany for maneuvers.
NATO deploys US nuclear missiles in Western Europe to counter Soviet and communist build up in the East.
NATO promotes democracy in Eastern Europe and over the next 14 years expands membership to ex-Soviet nations.
This saw NATO's first military engagement.
Operation Allied Force was a series of air strikes aimed at stopping the ethnic cleansing that was occurring during the Kosovo War.
The series of four co-ordinated terrorist attacks in the United States saw NATO invoke Article 5 for the first time.
